1. Field of Invention
The present invention relates to partitioning between zones in ovens, furnaces and high temperature equipment.
2. Description of the Prior Art
In furnaces or other types of high temperature equipment, it has often been the practice to partition off various zones depending on heat and usage requirements. So far as is known, curtain wall members, baffles or partitions employed in the past have been in the form of rigid refractory fiber boards and blankets supported by a rigid frame often employing water tubes for cooling purposes.
Several problems were presented by this approach. In the event that the furnace load or its manipulators stuck or came into contact with one of these rigid partitions or wall members, the refractory boards were damaged and the entire wall structure typically rendered useless. Also, water in tubes in the frame posed the danger of potentially harmful water leaks. Further, even if the water tubes were never damaged or leaking, heat was absorbed in them, causing heat loss from the zone being heated, adversely affecting the uniformity of heat distribution in the heated zone.
Attempts were made to use refractory fiber blankets, formed into suspended unitary walls by overlapping and attaching adjacent blanket segments and suspending them about a heated zone. However, the material of the blankets did not exhibit sufficient tensile strength, even when sewn together with refractory yarns or threads, for self-support in suspension for periods of use longer than several weeks. Further, the fibers in the blanket became brittle and failed due to high temperatures. Again, if the unitary wall were struck by a furnace load, such as a billet, the wall was in effect then useless and an entire replacement wall was needed.
Refractory cloths or tape strips woven from continuous filament, amorphous silica products have recently been developed. Research has been done into their use as inlet and outlet curtains in openings for movement of workpieces in and out of industrial furnaces. The purpose of these curtains was intended to reduce radiation and convection heat losses from the furnace interior and cause some reradiation of heat back into the furnace, while still allowing movement of workpieces in and out of the furnaces. So far as is known, however, these fabric curtains have not been felt suitable for use in furnace interiors for insulative walls or baffles, because of their permeability to heat due to their relatively thin construction caused by the size of the fibers used in making the woven cloths or strips. Further, when exposed to high service temperatures, these fabrics tended to become brittle and easily damaged. Gas velocities within the furnace enclosure tended to blow the thin fabrics about, reducing their effectiveness.